1. Field of the Invention
The present invention relates to an oil supply apparatus for a linear compressor, and more particularly to an oil supply apparatus for a linear compressor which is cost effective and improves productivity by excluding elastic members and thus simplifying an assembly process.
2. Discussion of the Background
In order to improve the mechanical efficiency of compressors, there have been numerous studies for supplying sufficient amounts of oil to a friction portion between a cylinder and a piston.
Referring to FIGS. 1 and 2, an example of a conventional linear compressor provided with an oil supply unit will be described.
In FIG. 1, in a predetermined-shaped hermetic vessel C, a compressor unit 10 is horizontally disposed, and an oil supply unit 30 is fixedly installed at a lower side of the compressor unit 10.
An oil pocket P provided in the compressor unit 10 is connected to the oil supply unit 30, and through the oil pocket P, oil O is supplied to a friction portion on between a cylinder 11 and a piston 17.
More specifically, a piston spring 16 is provided at one side in the hermetic vessel C, and spring supporters 15 are respectively fixed to an upper and a lower portion of an inner side of the piston spring 16.
A rear-end portion of the piston 17 which is connected to magnets 18 as a single body is fixed to a center portion of the inner side of the piston spring 16.
The cylinder 11 is provided at an outer side of the piston 17 in order that the piston 17 may reciprocate therein. On a portion of an outer circumferential surface of the cylinder 11, there are provided a plurality of oil flow holes 11a that connect an outer and an inner sides of the cylinder 11, and an upper and a lower portions of the cylinder 11 are respectively fixed by a flange 12.
An inner lamination 13 is fixed to an inner wall of the flange 12, and a stator core (an outer lamination) 14 wherein a stator coil 14a is provided is fixed to a portion of an outer circumferential surface of the flange 12, having a predetermined interval with the inner lamination 13. Thus, the piston 17 properly operates between the inner lamination 13 and the stator core 14.
At the other side of the cylinder 11, a valve section 19 and a muffler 20 are fixedly provided, and a refrigerant gas flows through a refrigerant flow pipe 21 provided at one side of the muffler 20 into the valve section 19.
An oil flow path 12a provided in a predetermined portion of one side of the flange 12 has end portions which respectively communicate with the oil supply unit 30 and with one side of the oil pocket P, and the other side of the oil pocket P communicates with one end portion of an oil exhaust path 12b provided in a portion of the other side of the flange 12.
Now, the oil supply unit 30 applied to the conventional compressor will be described with reference to FIGS. 1 and 2.
An oil-mass 32 in which an oil path 32a is provided is inserted in a center portion of a cylindrical and hollow oil supply pipe 31, so that the oil-mass 32 may reciprocate in accordance with the vibration of the compressor unit 10.
A first cover 33 having an oil flow hole 33a in a predetermined portion thereof is fixed to an end portion of an oil flow side of the oil supply pipe 31, and is supported by a predetermined portion of the spring supporter 15 fixed to the lower portion of the inner side of the piston spring 16.
A second cover 34 having an inner oil exhaust hole 34a communicating with the oil flow path 12a of the flange 12 therein is fixedly coupled with an end portion of an oil exhaust side of the oil supply pipe 31, and is fixed to the flange 12 by a plurality of bolts (not shown).
Between the oil-mass 32 and the first cover 33, there are provided an oil flow valve 35 which selectively opens/closes the oil flow hole 33a of the first cover 33 and a flow-side elastic member 36 such as a compression coil spring which elastically supports the oil flow valve 35.
Similarly, between the oil-mass 32 and the second cover 34, there are provided an oil exhaust valve 37 which selectively opens/closes the inner oil exhaust hole 34a of the second cover 34 and an exhaust-side elastic member 38 which has the same material as the flow-side elastic member 36 and elastically supports the oil exhaust valve 37.
The oil pocket P, i.e. the space between the cylinder 11 and the flange 12, communicates with the inner part of the cylinder 11 through the oil flow holes 11a.
The numerals 39 and 39' are an oil flow tube and an oil exhaust tube, respectively.
The operation by which oil is supplied to the friction portion between the cylinder 11 and the piston 17 by means of the oil supply unit 30 disposed at the outer side of the compressor unit 10 of the oil supply apparatus of the conventional linear compressor is as follows.
First, the piston 17 continuously reciprocates in the cylinder 11 in accordance with general operation of a linear motor, causing flow, compression and exhaust of refrigerant gas to be repeatedly accomplished. At this time, when the compressor unit 10 vibrates in accordance with the continuous reciprocation of the piston 17, the oil-mass 32 inserted in the oil supply pipe 31 moves in the horizontal direction.
Specifically, when the oil supply pipe 31 moves in the direction Q, the oil exhaust valve 37 moves in the direction P, as shown in FIG. 2, as the exhaust-side elastic member 38 of the oil supply pipe 31 is compressed, as shown in FIG. 3A, and simultaneously the flow-side elastic member 36 with the oil flow valve 35 moves in the direction P, thus the oil flow valve 35 is separated from the first cover 33.
The pressure between the oil flow valve 35 and the oil exhaust valve 37 is lowered, and accordingly a certain amount of oil filled in a bottom part of the hermetic vessel C is flowed into the first cover 33 through the oil flow tube 39, and thereto into the oil path 32a of the oil-mass 32 passing through an oil pass groove (not shown) provided on a portion of an outer circumferential surface of the oil flow valve 35, for thereby filling the oil path 32a.
On the other hand, when the oil supply pipe 31 moves in the direction P, the oil flow valve 35 moves in the direction Q, as shown in FIG. 2 and thus is compressed to a side of the first cover 33, as the flow-side elastic member 36 of the oil supply pipe 31 is compressed, as shown in FIG. 3B.
At the same time, since the exhaust-side elastic member 38 and the oil exhaust valve 37 move in the direction Q in FIG. 2 and the oil exhaust valve 37 is separated from the oil-mass 32, oil filled in the oil path 32a of the oil-mass 32 is flowed into the oil pocket P, passing through an oil pass groove (not shown) formed on a portion of an outer circumferential surface of the oil exhaust valve 37 and through the oil flow path 12a of the flange 12. The oil flowed into the oil pocket P is the supplied into the cylinder 11 passing through the oil flow holes 11a and into the friction portion between the piston 17 and the cylinder 11.
While, a portion of the oil flowed into the oil pocket P is transferred through the oil exhaust path 12b in the flange 12 and externally exhausted through the oil exhaust tube 39'.
However, the conventional apparatus requires the elastic members at each end side of the oil-mass in order to allow the oil-mass to reciprocate in the oil supply pipe, thereby increasing the manufacturing costs. In addition, the first and second covers need to be compressedly inserted into the end portions of the elastic members when sufficient elasticity is given to the oil-mass, whereby the productivity is degraded due to difficulty of the fabrication.